Shower Pipe Size – The Basics

Today we’ve got a nice, short, and easy one. We’re talking about showers and how to install them – specifically, plumbing. Having the proper shower pipe size is vital to properly install your bathroom’s pipework. Because you’re going to be conjoining all of your bathroom’s piping into a single master pipe, it’s important that you get the proper size. Too big and you have poor water pressure, and too small and you’ll have too much water pressure.

The standard shower pipe size in the UK is 15mm, while other pipework (toilet waste line) in your bathroom will most likely be 22 mm.

There’s not much more to say, but we’ll cover all of the important bits, so stay tuned.

Proper Shower Pipe Size

As you likely know (and we mentioned already) the size of your shower pipe should be 15mm in most cases. There are a few exceptions, however, that you’ll need to take note of:

  • In the 1970s, the UK changed their standard plumbing measurement system from Imperial to metric.
    • That means that what was formerly a .5″ and .75″ pipe would now be 15 or 22 mm.
    • Additionally, if you’re in an old home with old plumbing, you’ll need to adapt. Either buy and install all new plumbing, or get the right size measured in Imperial.
  • Irish pipe size varies slightly from the rest of the UK.
    • Irish standards use 14.7 mm and 21 mm, respectively. That’s right – they’re a bit smaller.
  • Depending on your source of water, the pipe size will vary.
    • A tank or cylinder heater requires a 22 mm pipe, otherwise it won’t provide a good flow rate.
    • A combi/boiler needs 15 mm to ensure proper pressure and flow rate.

Final Thoughts

As promised, that’s it! A nice, short solution, provided in under 2 minutes of reading. While shower pipe size isn’t a super complicated topic (contrary to what some plumbers may say), there are important factors to take into account. Where you live, what provides you with hot water, and when your home’s plumbing was installed will all play a role.

If you’re in the UK, you’re going to be working with standard metric measurements. Irish readers, on the other hand, will need slightly smaller pipes to accommodate for their unique plumbing. And keeping in mind what it heating your water will play a massive role in what size pipe you use. If left ignored, you’ll be faced with poor water pressure and flow rate – which nobody wants.

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About the Author Harry Thompson

Involved in home renovations throughout his life, Harry is an expert in everything to do with home and garden DIY. In his spare time, he enjoys cooking and tending to his garden.